Compressor-controlling mechanism



Nov. 20, 1928. 1,692,263

F. D. HOLDSWORTH COMPRESSOR CONTROLLING MECHANI SM Original Filed Jan. 25, 1924 QM: 5s

Patented Nov. 20, 1928.

UNITED STATES PATENT DFFICE.

FRED D. HOLDS'WOBTH, OF GLAREMON'I, NEW HAMPSHIRE, ASSIGNOR T SULLIVAN MACHINERY COMPANY, A CORPORATION OF MASSACHUSETTS.

COMPRESSOR-CONTROLLING MECHANISM.

Application filed January 25, 1924, Serial No. 688,682. Renewed June 6, 1928.

My invention relates to compressor con- An object of my invention is to providean improved compressor controlling mechanism. Another object of my invention 1s to provide an improved means for controlling the starting and stopping of a compressor in accordance with the demands for compressed air and improved means also controlled by the starting and stopping of the compressor for controlling the unloading and loading thereof. A further object of my invention is to provide an improved electro-pneumatic control means for the loading and unloading of the compressor. These and other objects and advantages of my invention will hereinafter more fully appear.

In the accompanying drawing I have shown for purposes of illustration one form which my invention may assume in practice.

In these drawings,

Fig. 1 is a view mainly in elevation but partially in section and a compressor system provided with one illustrative form of my improved controlling means, the electric circuits being shown diagrammatically.

Fig. 2 is an enlarged detailview of parts shown in section.

In the embodiment of my invention which I have elected to show for purposes of illustration I have shown the same applied to a compressor 1 having a cylinder 2 in whose bore 3 a piston 1 is adapted to be reciprocated by means of a crank shaft 5 and operative connections not fully shown. The compressor discharges by way of a pipe 6 to the receiver 7 through valve mechanism 8 of any suitable form. The admission of air to the compressor cylinder takes place past inlet valves 9 of any suitable construction, these valves being shown in a simplified form herein and being normally held closed by springs 10 save when open by reason of the reduction of pressure within the cylinder bore during the suction stroke of the piston. For the purpose of opening the inlet valves and holding them open so as to effect unloading of the compressor when desired, I provide pistons 11 reciprocable in cylinders 12 to which air may be admitted by wayof connections 13 under control of a mechanism 21 and 22 to the motor.

14 hereinafter more fully described, the pass age 13 being connected to the receiver as indicated at 15 through the valve mechanism 14.

The compressor is driven by a mbtor diagrammatically shown at M, which motor is provided with starting means having a series of resistances 16, 17, 18 and 19, all of which are in circuit when the main switch 20 closes the circuit through the main wires It will be noted that switch 20. The main line switch has movable therewith a supplemental switch 27 which controls a circuit through a solenoid 28 which serves in turn to close the switch 29 shunting the first resistance 16. The switch 29 carries with it a supplemental switch 30 which closes an operating circuit which causes the next successive resistance 17 to be shunted and as each successive resistance shunting switch closes, it, by means of a pilot switch movable therewith, brings about the completion of the circuit through means for closing the next resistance shunting switch. As devices of this type are now quite well known, no further description of the details is believed necessary save that it may be said that the movement of each of the resistance shunting switches is controlled by dash pot means diagrammatically shown in Fig. 1 and of such nature that closing movements of the switches take place relatively slowly while the opening movements are allowed to take place sharply. An examination of the connections disclosed will show that opening of the main line switch will cause instantaneous opening of all the resistance shunting switches and accordingly each time that the motor is stopped, it must be brought up to speed gradually b the cutting out of the full resistance. t will be observed that by reason of the presence of the dash pot mechanisms described a sufficient -time lapse between the closing of the mainswitch and the cutting out of all resistance is provided to permit the motor to come up to running speed.

It will be noted that the last resistance shunting switch carries a sup lemental switch which closes a circuit t rough a solenoid 36 and this-solenoid controls the movements of an armature or plunger 37- which is secured to a rod 38 which passes through an Opening 39 in the top of a cover or housing member 40. This housing member is secured upon the top of and partially encloses a pilot valve mechanism of the well-known type disclosed in the patent to John L. Osborne 1,141,97 5. In view of the disclosure of this pilot mechanism in the patent, it is believed to be unnecessary to enter into a detailed description of its structure, and it will suflice to state that receiver pressure admitted to a chamber 41 through the connection 15 is adapted when a diaphragm 42 is forced upward by the pressure of the air within the chamber to pass through an opening 43 in a plunger 44 and through openings 45 in a plate valve 46 and thence into the connection 13, while when downward movement of the diaphragm 42 takes place, the plunger 44 will be depressed and moved into engagement with the upper surface of the plate 46 so that the latter is moved away from seating engagement over a series of ports 47 which lead to an exhaust 48 and so that the plate seals ofi passage of air through the bore 43,'a spring 49 being provided of sufficient strength to maintain the plate against the end of the plunger 44 against the air pressure. It will be further noted that the relatively heavy spring 50 acts upon a shoulder 51 at the lower end of the stem 38 while the latter acts upon a member 52 which rests upon the diaphragm.

It will be understood that the spring 50 may be placed under such compression that it will almost be able to overcome the pressure of the'air beneath the diaphragm 42when the pressure within the receiver is the minimum desired during the operation of the compressor systemso that the solenoid 36 will have to exert relatively little downward force toenable the pressure within the chamber 41 to be overcome and the compressor to be loaded by the venting of the pressure beneath the pistons 11. For the'purpose of enabling the compressor to be started unloaded when the pressure in the receiver is less than sufiicient to overcome the pressure of the spring 50, for example, at times when the compressor has been shut down for some time, resort may be had to the use of a bypass mechanism of the general type shown in my earlier Patent 1,- 363,204 whereby in one position of such a valve communication between the pipes 26 and 13 may be open to supply air directly beneath the pistons 11 and at which time the portion of the pipe 13 below the valve mechanism 53 will be out off from communication with the portion thereabove, while in another position the valve 53 may cause an interconnection of the pipes 15 and 13 through the valve mechanism 14 while closing off communication between the pipes 26 and 13.

From the description which has been given the mode of operation of my invention will be readily apparent. When the receiver pressure is in excess of the predetermined desired amount the pilot switch 24 will be forced open and as a result there will be no current flow through the solenoid 36. Accordingly the diaphragm 42 will be forced upwardly per mitting fluid to pass through. the passage 43 beneath the pistons 11 to effect unloading of the compressor. When the receiver pressure falls to the predetermined desired limit, the

pilot switch 24 will be closed by the dia-- phragm 25 and the main line switch will close first and then the automatic mechanism described Will successively cut out the resistances and finally close the circuit by means of switch 35 through the solenoid 36. This will result in the plunger 37 aiding the spring 50 to move the diaphragm 42 downwardly and so supply of pressure fluid beneath the pistons 11 will be interrupted and the space below them in the cylinders 12 will be vented and the compressor loaded. 4

While I have in this application specifically described one form which my invention may assume in practice. it will be understood that this form of the same is shown for purposes of illustration and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a compressor controlling system, a compressor, electric driving means therefor, pneumatic unloading means for said compressor, comptroller means for said driving means, and means including a spring controlled by said co-ntroller means for controlling said unloading means, and comprisingmeans constantly biased toward one of its positions by compressor discharge pressure.

2. In a compressor controlling system, a compressor, unloading means therefor, and combined electric and discharge pressure controlled pilot means for controlling the operation of said unloading means, said pilot means having yieldable means associated therewith and said electric controlling means being adapted to exert its actuating force in the same direction as the pressure of said yielding means.

3. In a compressor controlling system, a compressor, unloading means therefor, and combined electric and discharge pressure controlled pilot means for controlling the operation of said unloading means, said pilot loo lUi)

' tric control being means having its electric and pressure control devices coaxially arranged, and said elecgoverned by the compressor discharge pressure.

4. In combination, valve means operative alternatively to supply pressure fluid or to exhaust pressure fluid previously supplied, and controlling means therefor including a member variations in whose position cause changes in the functioning of said valve means, said member having a :urface exposed to and being movable under certain conditions by a pressure whose fluctuations it is desired to control, adjustable means normally opposing said pressure, and means intermittently opposing said pressure.

5. In combination, valve means operative alternatively to supply pressure fluid or to exhaust pressure fluid previously supplied, and controlling means therefor including a member variations in Whose position cause changes in the functioning of said valve means, said member having a surface exposed to and being movable under certain conditions by pressure Whose fluctuations it is desired to control, means separate from said member normally opposing said pressure but insuflicient to overcome it, and means intermittently opposing said pressure and adapted cumulatively with said previously mentioned means to overcome said pressure.

6. In combination, in a compressor controlling system, a compressor, unloading means therefor including a controlling element exposed to compressor discharge pressure which tends to move it in one direction, and electro-magnetic control means coaxial to said controlling element for controlling said unloading means including means also acting upon said element when the compressor has run a predetermined time and tending to move it in the opposite direct-ion.

7. In a compressor controlling system, a compressor, unloading means therefor pilot means for controlling operation of said unloading means, and coaxially arranged-electromagnetic and discharge pressure controlled means for controlling said pilot means, said coaxially arranged means being adapted to influence said pilot means in opposite directions.

8. In a compressor controlling system, a compressor, unloading means therefoiyand combined electric and discharge pressure controlled pilot means for controlling the operation of said unloading means comprising'a movable element having a surface subjected to discharge pressure, adjustable yieldable means opposed thereto, and electric actuating means acting cumulatively with said yieldable means in opposition to discharge pressure, said actuating means being governed by compressor discharge pressure.

9. In a compressor controlling system, a compressor, unloading means therefor, and combined electric and discharge pressure controlled pilot means for controlling the operation of said unloading means comprising a movable element having a surface subjected to discharge pressure, a spring opposing the yielding of said element to said pressure, and an electric motor adapted upon current being supplied thereto to exert its actuating force in the same direction as the pressure of said spring.

10. In a compressor controlling system, a compressor, unloading means therefor, .an electric motor for driving said compressor, a starting switch mechanism for said motor, a valve mechanism adapted in one position to supply pressure fluid to said unloading means and in another position to vent pressure fluid from said unloading means, and means for actuating said valve mechanism comprising a diaphragm having a surface subjected to discharge pressure and tending to move said valve mechanism in one direction, and a solenoid which when energized tends to actuate said valve mechanism in the opposite direction, said solenoid being deenergized when the motor is stopped.

In testimony whereof I affix my signature. ,7

FRED D. HOLDSWORTH. 

